<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
					
					table,tr,td
					{
						border: 1px solid black;
						border-collapse: collapse;
					}
					
				</style>
	</head>
	<body>
		<script>
					// 1. 数组
					var arr1 = new Array();
					console.log(arr1.length)
					arr1[0] = "张三";
					arr1[1] = 1;
					arr1[2] = "王五"
					console.log(arr1)
					console.log(arr1.length)
		
					var arr2 = new Array(3);
					console.log(arr2[0])
		
					var arr3 = new Array(10, 20, 30, 40, 50)
					console.log(arr3[0])
		
					var arr4 = [10, 20, 30, 40]
					console.log(arr4)
		
					var arr5 = [
						[1, 2, 3],
						[4, 5, 6],
						[7, 8, 9],
					];
					var stus = [{
							id: 1,
							name: "张三",
							age: 18
						},
						{
							id: 2,
							name: "李四",
							age: 19
						},
						{
							id: 3,
							name: "王五",
							age: 20
						},
					]
					console.log(stus)
		
					document.write("<table>");
					document.write("<tr>");
					document.write("<td>");
					document.write("学号");
					document.write("</td>");
					document.write("<td>");
					document.write("姓名");
					document.write("</td>");
					document.write("<td>");
					document.write("年龄");
					document.write("</td>");
					document.write("</tr>");
					for (var i in stus) {
						var stu = stus[i]
						document.write("<tr>");
						document.write("<td>");
						document.write(stu.id);
						document.write("</td>");
						document.write("<td>");
						document.write(stu.name);
						document.write("</td>");
						document.write("<td>");
						document.write(stu.age);
						document.write("</td>");
						document.write("</tr>");
					}
					document.write("</table>");
		
					// 练习:
					// 定义一个数组存放一些国家名字 
				</script>
	</body>
</html>
